Hepatomas have been shown to have a number of alterations in phospholipid composition. A key change is an increased level of lysophospholipids which are potent detergents. Further, the fatty acid composition of the phospholipid, in part determined by the monoacyl-diacyl (Land's cycle), is different from normal liver. Both of these observations suggest changes in the metabolism of the lysophospholipids. It is the purpose of this project to identify the underlying alterations in lysophospholipid metabolism that leads to the unusual chemistry and structure of these lipids. Also, the synthesis and utilization of polyunsaturated fatty acids will be examined, since they too influence the physical-chemical nature of the membrane. The basic procedure will be to obtain Morris hepatoma in host rats, prepare and characterize subcellular fractions, study the phospholipases A and acyl CoA lysophospholipase acyl transferase activities, and compare these results with those obtained using normal rat liver. Further, the conversion of linoleic acid to arachidonic acid (and other long chain polyunsaturates) will be measured. Most studies will be done using radioactive substrates and identification of the products using thin-layer and gas-liquid chromatography. The production of lysophospholipids by hepatoma cells in culture and the effect of these compounds on growth characteristics of normal liver cells will be examined. The characteristics to be studied are rate of growth and contact inhibition.